The most common type of storage battery, found in almost every vehicle, is the lead-acid battery. This battery comprises a lead dioxide positive electrode, a lead metal negative electrode, and sulfuric acid for the electrolyte. The advantages of the lead-acid battery are numerous. It is low cost, maintenance-free, and provides dependable service over a wide temperature range.
Unfortunately, the lead-acid battery also has its drawbacks; The electrolyte, sulfuric acid, is highly corrosive. The energy density of the battery is low, thus limiting its use in mobile equipment. Finally, its operation is handicapped by the evolution of hydrogen at the negative electrode when the battery is overcharged.